1. Field of the Invention
This application relates to heat-age stable water borne coating compositions and polymers thereof with good adhesion, block resistance, and hiding. In other approaches, the application relates to low or no VOC heat-age stable water borne coating compositions and polymers thereof with good adhesion, block resistance, and hiding with reduced levels of pigments.
2. Description of Related Art
Paints typically contain four ingredients: a carrier liquid, a binder, one or more pigments, and one or more additives to provide the paint with desired properties. Each such ingredient may comprise a single component or several different components mixed into the paint.
The carrier liquid is a fluid component of the paint which serves to carry all of the other paint components. The carrier liquid is part of the wet paint and usually evaporates as the paint forms a film and dries on a surface. In latex paints, the carrier liquid is usually water. In oil-based paints, the carrier liquid is usually an organic solvent.
The binder component of paint is what causes the paint to form a film on and adhere to a surface. In a latex paint, the binder comprises a latex resin, usually selected from acrylics, vinyl acrylics, or styrene acrylics or blends thereof in varying ratios. In a latex paint, the latex resin particles usually are in a dispersion with water as the carrier liquid.
Pigments provide the paint with both decorative and protective features. Pigments are solid particles used to provide the paint with various qualities, including but not limited to color, opacity, and durability. The paint may also contain other solid particles such as polyurethane beads or other solids. Pigments and other solids add bulk to the paint and their levels are related to the gloss or flatness of the paint.
A multitude of other additives may be included as needed for particular application in the paints. The additives are typically used at relatively low levels in the paint formulation, but contribute to various properties of paints, including but not limited to, rheology, stability, paint performance, and application quality.
The pigments used in a water-borne paint composition typically include an opacifying pigment, which imparts opacity or hiding to the paint film. One of the most effective and, hence, one of the most widely used opacifying pigments is titanium dioxide or TiO2. Although very effective, titanium dioxide is expensive and in many applications is the most expensive component of a water-borne paint composition. Accordingly, it is desirable to achieve the desired degree of hiding and other paint characteristics using the least amount of titanium dioxide possible. Various paint compositions have been proposed for utilizing titanium dioxide more efficiently; however, most of these paint compositions are less desired and such compositions also tend to be less stable over time.